GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 frequencies. For this reason, we focus here on the development of a new mathematcal formulaton able to describe the source tme functon contributon contained in the far feld strain domain, leading to forward modelling of tme integrated strain spectra and evaluaton of source parameters. We validated the technique on two case-studies, for earthquakes in magnitude range , by comparing the results with estmates from standard seismic instruments. When analysing earthquakes recorded on an of-shore, long cable during a 1-month DAS survey in Chile, results exhibit scale invariant stress drop distributon between seismic moment and corner frequency estmates, with an average of . Moreover, moment magnitude estmatons agree with results from local seismic statons. The second case study involves DAS data acquired on a short cable ( ) deployed in the Irpinia region in the Southern Apennines during a 5-month temporary experiment. Here data show a dominance of site efects resultng in an apparent corner frequency around , while the low frequency content of signals gives estmates of moment magnitude in agreement with seismic statons. Nevertheless, the modelling of local site efect through a parametric EGF approach allows to determine corner frequencies for the largest magnitude events in the catalogue. Overall, results highlight the potental of DAS systems in characterizing the seismic ruptures over diferent space scales, exploitng the redundancy of informaton available from the very-high spatal resoluton of recordings. References Ajo-Franklin, J. B., Dou, S., Lindsey, N. J., Monga, I., Tracy, C., Robertson, M., Rodriguez Tribaldos, V., Ulrich, C., Freifeld, B., Daley, T., & Li, X; 2019: Distributed Acoustc Sensing Using Dark Fiber for Near-Surface Characterizaton and Broadband Seismic Event Detecton. Scientfc Reports , 9 (1). htps://doi.org/10.1038/s41598-018-36675-8 Biondi, E., Zhu, W., Li, J., Williams, E.F., Zhan, Z.; 2023: An upper-crust lid over the Long Valley magma chamber. Science Advances htps://doi.org/10.1126/sciadv.adi9878 Current, G., Jousset, P., Napoli, R., Krawczyk, C., & Weber, M.; 2021: On the comparison of strain measurements from fbre optcs with a dense seismometer array at Etna volcano (Italy). Solid Earth , 12 (4), 993–1003. htps://doi.org/10.5194/se-12-993-2021 Hartog, H.A.; 2017: An introducton to distributed optcal fbre sensors (A. H. Hartog, Ed.). CRC Press. Hudson, T. S., Baird, A. F., Kendall, J. M., Kufner, S. K., Brisbourne, A. M., Smith, A. M., et al.; 2021: Distributed Acoustc Sensing (DAS) for natural microseismicity studies: A case study from Antarctca. Journal of Geophysical Research: Solid Earth, 126, e2020JB021493. htps://doi.org/ 10.1029/2020JB021493 0.4 − 4.3 150 km Δσ = ( 0.8 ± 0.6 ) MPa 1 km 5 Hz